Z03.0.0X.6C-11
Operating manual GE xxx serie
page 7 of 12
The diaphragm, which establishes a connection between the electrolyte and the liquid to be
measured, can be designed in different ways. Clogging or soiling of the diaphragm is a frequent
cause of a malfunctioning or sluggish electrode.
Always handle the glass membrane with extreme care. The so-called source layer forms there. This
is crucial for the measurement and must always be kept moist.
3.3 Further information
A pH electrode is a wear part. If the signal is very slow or the required values are no longer
observed after careful cleaning and possible regeneration, the electrode must be replaced. When
using the electrodes, be aware that various substances in aqueous solutions can corrode glass and
that chemicals can produce a chemical reaction with the KCl solution in the electrode, which can
result in blockage of the diaphragm.
Examples:
• In solutions that contain proteins, such as for measurements in medical and biological
applications, KCl can cause denaturation of the protein.
• Coagulated paints
• Solutions that contain high concentrations of silver ions
Substances that accumulate on the glass membrane or the diaphragm affect the measurement and
must be removed regularly. This can be achieved for example with automatic cleaning systems.
3.4 Service life
The service life of electrodes is normally at least 8 to 10 months. When cared for
properly, this can usually increase to more than 2 years. The actual life will vary
depending on the particular application.
Extreme pH values and high temperatures accelerate the aging process.
4
Operating and Maintenance
4.1 Measuring and storing
The pH-electrodes have been tested and have been subordinated strict quality controls in all
manufacturing-steps
To keep the optimum efficiency and accuracy for a long time take care of the following points:
Remove the
storing
protection-cap
and rinse the shaft and pH-glass-diaphragm with distilled
water.
Important!
The pH-glass-diaphragm has to be kept wet. When not in use the electrode must be
stored in 3 mol/l KCl solution. (GE 103 in 1 mol/l KNO
3
). If the pH-glass-diaphragm dried out,
the performance and the responsiveness are affected. To re-moisten the electrode store it in 3
mol/l KCl solution for 24 hours (GE 103 1 mol/l KNO
3
).
A longer storage of a combination-electrode or a reference-electrode in distillated water will
deplete them of KCl. Please refill KCl-electrolyte (saturated or 3 mol) in time
Do not touch the glass-diaphragm!
Damages on the surface and attrition affect the
performance negatively and might even destroy the electrode.
Before usage perform a visual check of the pH-electrode. If there are air-bubbles in the pH-
glass-diaphragm or the outer reference-electrode you can get them out by shaking the
electrode downward.